Using data from an online survey of grocery store customers in Logan, Utah, we estimate the marginal effects on willingness to pay (WTP) for continued use of plastic grocery bags, and the marginal effects on willingness to accept (WTA) for switching to reusable grocery bags. We find both non-parametric and parametric evidence suggesting that individuals respond quite dramatically to moderate plastic-bag tax rates and reusable-bag subsidy rates. All else equal, older and lower-to-middle income individuals, as well as larger-sized households, are more likely to switch to using reusable bags exclusively when faced with a tax on plastic bags. Lower-to-middle income individuals, as well as women in general, are more likely to switch away from using plastic bags when provided with a subsidy for reusable bags. Our results help quantify the extent to which plastic bag taxation and reusable bag subsidization might induce shoppers to switch from plastic to reusable bags for their grocery trips.